This invention relates to friction welding and, more specifically, to friction welding of one or more structural members to form a tailored blank.
Hogout machining generally refers to a process of forming a structure or structural member by removing excess material from a piece of stock material, such as a plate or block, to arrive at the desired configuration and dimensions. Oftentimes when practicing hogout machining, the dimensions and configuration of the final structure are such that appreciable amounts of material must be removed. Thus, while hogout machining provides a method for forming structures or structural members having complex configurations, hogout machining can be costly due to the relatively large amount of excess material or scrap that typically must be removed and because the machining process can be time consuming and labor intensive. Hogout machining also can cause excessive wear on the cutting machine and tools, which can result in machine downtime and/or tool breakage that in turn can adversely affect the tolerances of the finished structure. In addition, the availability of stock sizes of material limits the overall dimensions of a structure or structural member formed by hogout machining.
In seeking to reduce material waste and machining times, other methods are used for forming the stock material to be used in machining a structure or structural member. For example, one method is machined forging, which refers to the process of machining a part from a piece of forged stock material that approximates the final configuration. When machined forging is used, the amount of machining can be reduced because the forged stock material can be hand or die forged to dimensions that more closely approximate the desired dimensions of the finished assembly. However, the production of forged stock material can be time consuming and labor intensive and, in the case of die forgings, can require the production of costly forging dies. Die forgings can require ultrasonic inspection, as the forging process can cause internal cracks or other defects. Additionally, both die and hand forging can cause residual stresses in the forged stock material that can remain in the finished structure or structural member. Residual stresses can necessitate slower cutting speeds when hogout machining and can adversely affect the material properties and tolerances of the finished structure.
Many complex machined parts are curved due to the mold line contour that is required for many parts, in particular, fuselage frames or longerons. The manufacture of such curved structures using hogout machining results in great material waste.
There is a need for a method of manufacturing curved machined structures with a minimum of material waste.